blowing oil out of breather cap

edj1993 · 07-03-2008, 09:00 PM

I recently purchased a'63 Super 88 with what I believe is the 394 hi-comp. The motor was supposedly "rebuilt" recently. It runs beautifully but I am getting oil blowing from the breather cap at the front of the engine. There seems to be a fair amount of blowby coming from the breather but I am not sure what's normal. Also, I have looked at pics of other 394's of this vintage and noticed tht the breather tube comes up at an angle-mine comes straight up(90 degrees). I dont really want to tear into the engine yet.. Is there something I am missing ??

Oldsfan · 07-04-2008, 10:10 AM

Every early Rocket V8 I have ever had has had blow-by.

Paul

rocketraider · 07-04-2008, 10:46 AM

Second that. It was a known problem after those engines got some miles on them. From what I've read a lot of it traced back to valve guides.

What's your oil consumption? When my blue 64 was running, it blew oil vapor all over the place but used only a quart every 1000 miles or so- definitely not enough to make me tear into it.

I think a lot of it is because of that weird PCV valve the 63-5 cars used. Cars I've seen with California semi-closed PCV generally don't fog as badly.

edj1993 · 07-07-2008, 06:04 PM

Thanks, guys; however, this is more than just blow-by.. It is coating the whole engine compartment with oil, and it pools in the valleys at the base of the breather cap, intake manifold, etc.. The hood insulation is also pretty saturated. Also, any ideas on the angle of the breather tube as mentioned above.

rocketraider · 07-07-2008, 07:09 PM

Is the foam filter in place in the oil fill cap? If it's blowing oil as bad as you say it would soon saturate that, though.

I'd check the oil drainbacks in the heads just in case it's pooling in the rocker area and sucking in around valve guides.

Have you done a compression check? If it was in fact rebuilt, sounds like either rings have not seated or one is cracked.

Is the PCV flapper valve functioning? Take it loose and shake it; if it rattles it's probably OK, but I still think they're weird. Make sure the small vacuum line isn't plugged.

Wouldn't worry too much about the oil fill tube angle. Most I've seen angle off to the right side of the car, but my green Starfire has aftermarket A/C which required a modified fill tube. It's bent like a dogleg and I'm pretty sure came with the A/C installation kit.

edj1993 · 07-08-2008, 04:32 PM

Thanks Rocketraider.. The small vacuum line is not hooked up-would that make a difference ? If so, should this be hookd into the carb ". This car has the factory A/C so maybe that's why the breather tube is straight up. The breather cap has the steel wool type stuff in the top. I have even tried stuffing a plastic scrubber thing into the tube, but it still comes out.. I have not had the valve covers off so dont know bout the oil drain tubes.. I am going to run a comression test next.. thanks for your input.

rocketraider · 07-08-2008, 06:27 PM

The small vac line goes from the PCV valve to the back of the carb, or some years there's a vacuum port on the intake. It will affect it some because the PCV relies on that small amount of vacuum to help lift the flap off its seat as well as pulling some of the blowby gas back into the engine for reburn. Without it, the engine is not getting enough fresh air in via the aircleaner tube, and not allowing vapors to be sucked out of the valve cover and into the carb via that same tube.

The damn thing is just weird, but it apparently worked for a couple years until they decided to use a more conventional PCV system.

Hope hooking the PCV vacuum back up helps. It sure can't hurt.

Oldsfan · 07-08-2008, 07:13 PM

Mine have blown oil out the filler tube, too. It makes quite the mess. It is the result of too much pressure in the crankcase and it pushes the oil out the breather on the filler tube, because that is the only place it has to go, unless you have some weak seals, then it'll push it out at the seals. I took that steel wool lined cap and put on a "top hat" cap from a '67. That cuts down on it some. This is the second car I have done that to.

Paul

frdmftr · 07-09-2008, 08:53 AM

Also look at the valve covers themselves. The stock covers have a shield inside to 'help' keep oil blow at a minimum. I have aftermarket Edelbrock's and sure'nuf, they don't have the plates.

I get minimal fogging, carry roll of shop towels in trunk and a ziploc to store soiled ones in.

Jokers69 · 07-09-2008, 09:43 AM

Quote:

I have aftermarket Edelbrock's and sure'nuf, they don't have the plates.

My Moroso valve covers have baffle plates in them, so I ran one of the chrome caps with the PVC valve built in.

frdmftr · 07-09-2008, 09:53 AM

Good suggestion. I will convert mine as well. Anything helps.

07-03-2008, 09:00 PM	#1 (permalink)
edj1993 Junior Member Join Date: Apr 2008 Location: Indiana Posts: 18	blowing oil out of breather cap I recently purchased a'63 Super 88 with what I believe is the 394 hi-comp. The motor was supposedly "rebuilt" recently. It runs beautifully but I am getting oil blowing from the breather cap at the front of the engine. There seems to be a fair amount of blowby coming from the breather but I am not sure what's normal. Also, I have looked at pics of other 394's of this vintage and noticed tht the breather tube comes up at an angle-mine comes straight up(90 degrees). I dont really want to tear into the engine yet.. Is there something I am missing ??

07-04-2008, 10:10 AM	#2 (permalink)
Oldsfan Senior Member Join Date: Jul 2006 Posts: 508	Every early Rocket V8 I have ever had has had blow-by. Paul __________________ There's "Something Extra" about owning an OLDS! -- Visit the "Something Extra" website at: http://home.comcast.net/~oldsfan/MySite/62oldspage.html

07-04-2008, 10:46 AM	#3 (permalink)
rocketraider Oldsdruid Join Date: Dec 2007 Location: Danville Vajenya, the Last Capital of Dixie Posts: 348	Second that. It was a known problem after those engines got some miles on them. From what I've read a lot of it traced back to valve guides. What's your oil consumption? When my blue 64 was running, it blew oil vapor all over the place but used only a quart every 1000 miles or so- definitely not enough to make me tear into it. I think a lot of it is because of that weird PCV valve the 63-5 cars used. Cars I've seen with California semi-closed PCV generally don't fog as badly. __________________ I know absolutely nothing about Oldsmobiles. Just ask the owner of Oldspower.com

07-07-2008, 07:09 PM	#5 (permalink)
rocketraider Oldsdruid Join Date: Dec 2007 Location: Danville Vajenya, the Last Capital of Dixie Posts: 348	Is the foam filter in place in the oil fill cap? If it's blowing oil as bad as you say it would soon saturate that, though. I'd check the oil drainbacks in the heads just in case it's pooling in the rocker area and sucking in around valve guides. Have you done a compression check? If it was in fact rebuilt, sounds like either rings have not seated or one is cracked. Is the PCV flapper valve functioning? Take it loose and shake it; if it rattles it's probably OK, but I still think they're weird. Make sure the small vacuum line isn't plugged. Wouldn't worry too much about the oil fill tube angle. Most I've seen angle off to the right side of the car, but my green Starfire has aftermarket A/C which required a modified fill tube. It's bent like a dogleg and I'm pretty sure came with the A/C installation kit. __________________ I know absolutely nothing about Oldsmobiles. Just ask the owner of Oldspower.com

07-08-2008, 06:27 PM	#7 (permalink)
rocketraider Oldsdruid Join Date: Dec 2007 Location: Danville Vajenya, the Last Capital of Dixie Posts: 348	The small vac line goes from the PCV valve to the back of the carb, or some years there's a vacuum port on the intake. It will affect it some because the PCV relies on that small amount of vacuum to help lift the flap off its seat as well as pulling some of the blowby gas back into the engine for reburn. Without it, the engine is not getting enough fresh air in via the aircleaner tube, and not allowing vapors to be sucked out of the valve cover and into the carb via that same tube. The damn thing is just weird, but it apparently worked for a couple years until they decided to use a more conventional PCV system. Hope hooking the PCV vacuum back up helps. It sure can't hurt. __________________ I know absolutely nothing about Oldsmobiles. Just ask the owner of Oldspower.com

07-07-2008, 06:04 PM	#4 (permalink)
edj1993 Junior Member Join Date: Apr 2008 Location: Indiana Posts: 18	Thanks, guys; however, this is more than just blow-by.. It is coating the whole engine compartment with oil, and it pools in the valleys at the base of the breather cap, intake manifold, etc.. The hood insulation is also pretty saturated. Also, any ideas on the angle of the breather tube as mentioned above.

07-08-2008, 04:32 PM	#6 (permalink)
edj1993 Junior Member Join Date: Apr 2008 Location: Indiana Posts: 18	Thanks Rocketraider.. The small vacuum line is not hooked up-would that make a difference ? If so, should this be hookd into the carb ". This car has the factory A/C so maybe that's why the breather tube is straight up. The breather cap has the steel wool type stuff in the top. I have even tried stuffing a plastic scrubber thing into the tube, but it still comes out.. I have not had the valve covers off so dont know bout the oil drain tubes.. I am going to run a comression test next.. thanks for your input.

07-08-2008, 07:13 PM	#8 (permalink)
Oldsfan Senior Member Join Date: Jul 2006 Posts: 508	Mine have blown oil out the filler tube, too. It makes quite the mess. It is the result of too much pressure in the crankcase and it pushes the oil out the breather on the filler tube, because that is the only place it has to go, unless you have some weak seals, then it'll push it out at the seals. I took that steel wool lined cap and put on a "top hat" cap from a '67. That cuts down on it some. This is the second car I have done that to. Paul __________________ There's "Something Extra" about owning an OLDS! -- Visit the "Something Extra" website at: http://home.comcast.net/~oldsfan/MySite/62oldspage.html Last edited by Oldsfan : 07-08-2008 at 07:16 PM.

07-09-2008, 08:53 AM	#9 (permalink)
frdmftr Freedom Fighter Join Date: Feb 2007 Location: Nine Mile Falls, Washington Posts: 122	Also look at the valve covers themselves. The stock covers have a shield inside to 'help' keep oil blow at a minimum. I have aftermarket Edelbrock's and sure'nuf, they don't have the plates. I get minimal fogging, carry roll of shop towels in trunk and a ziploc to store soiled ones in. __________________ Mad Max Nine Mile Falls, Wa 67 Delta 88 Convertible

07-09-2008, 09:53 AM	#11 (permalink)
frdmftr Freedom Fighter Join Date: Feb 2007 Location: Nine Mile Falls, Washington Posts: 122	Good suggestion. I will convert mine as well. Anything helps. __________________ Mad Max Nine Mile Falls, Wa 67 Delta 88 Convertible

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